Air showers, hadronic models, and muon production

We report on a study about some characteristics of muon production during the development of extended air showers initiated by ultra-high-energy cosmic rays. Using simulations with the recent new version of the AIRES air shower simulation system, we analyze and discuss on the observed discrepancies between experimental measurements and simulated data.Comment: Presented at UHECR 2018 (Paris, Oct 2018

Enhancing the Pierre Auger Observatory to the 10^{17} to 10^{18.5} eV Range: Capabilities of an Infill Surface Array

The Pierre Auger Observatory has been designed to study the highest-energy cosmic rays in nature (E > 10^{18.5} eV). The determination of their arrival direction, energy and composition is performed by the analysis of the atmospheric showers they produce. The Auger Surface Array will consist of 1600 water Cerenkov detectors placed in an equilateral triangular grid of 1.5 km spacing. The aim of this paper is to show that the addition of a "small" area of surface detectors at half or less the above mentioned spacing would allow a dramatic increase of the physical scope of this Observatory, reaching lower energies at which the transition from galactic to extragalactic sources is expected.Comment: 21 pages, 5 figures, accepted for publication in Nucl. Instr. & Meth. in Phys. Res.